
    <nz-tree-select style="width: 250px"
      nzPlaceHolder="Please select"
      [nzDefaultExpandedKeys]="expandKeys"
      [nzDropdownMatchSelectWidth]="true"
      [nzDropdownStyle]="{ 'max-height': '300px' }"
      [(ngModel)]="value"
      [nzNodes]="nodes"
      [nzAsyncData]="true"
      (nzExpandChange)="onExpandChange($event)">
    </nz-tree-select>
  